Method of manufacturing multiple track, single gap magnetic heads

ABSTRACT

Two sub-assemblies, each comprising an identical, elongate compound housing and a plurality of similarly arranged elongate compound cores, are joined in face-to-face engagement with opposite end portions of the compound cores of one sub-assembly forming magnetic circuits, including an air gap, with opposite end portions of the compound cores of the other sub-assembly. Separation of the joined sub-assemblies substantially perpendicular to the plane of their face-to-face engagement at a position intermediate the opposed end portions of the combination cores results in the formation of two complete head assemblies.

United States Patent Braun et' a1.

[ July 25, 1972 [54] METHOD OF MANUFACTURING MULTIPLE TRACK, SINGLE GAP MAGNETIC HEADS [72] Inventors: Richard E.Braun, St. James; Lionel G.

Hopkins, Lake Grove; Neil J. Sheehan, Carle Place; Edward J. Sanchez, Long Island, all of NY.

[73] Assignee: Magnetic Head. Corporation, Hauppauge,

[22] Filed: June 25, 1971 211 Appl. No.: 156,809

[52] U.S.Cl. [51] Int. Cl. [58] Field of Search ..29/603, 179/100.2 C ....Gllb 5/42, H0lf7/06 ..29/603; l79/100.2 C;

340/174.l F; 346/74 MC [56] References Cited UNITED STATES PATENTS 3,417,465 12/1968 Glass ..29/603 3,534,470 10/1970 Faureetal...

3,475,815 1 H1969 Girdner ..29/603 3,249,987 5/1966 Duinker Primary Examirier-John F. Campbell Assistant Examiner-Carl E. Hall Attorney-Colton & Stone [5 7] ABSTRACT Two sub-assemblies, each comprising an identical, elongate compound housing and a plurality of similarly arranged elongate compound cores, are joined in face-to-face engagement with opposite end portions of the compound cores of one subassembly forming magnetic circuits, including an air gap, with opposite end portions of the compound cores of the other subassembly. Separation of the joined sub-assemblies substantially perpendicular to the plane of their face'to-face engagement at a position intermediate the opposed end portions of the combination cores results in the formation of two complete head assemblies.

3 Claims, 3 Drawing Figures PATENTEU JUL25 I972 3 57 575 INVENTORS. RICHARD E. BRAUN LIONEL G. HOPKINS J SHEEHA RD 1 SANC Giza/km BACKGROUND OF THE INVENTION The usual method of manufacture employed in the production of a multiple track, single gap magnetic head involves the separate formation and assembly of opposed housing sections with a plurality of core sections. A pair of housing sections are subsequently joined in face-to-face engagement with their respective core sections aligned to provide a plurality of magnetic circuits, including air gaps, defined by each aligned core section pair. Typically, the core sections assembled with one of the housing sections are wound with a transducing coil and are termed the active core sections while the core sections assembled with the other housing section simply provide a return path and are referred to as the inactive core sections. In many instances, both the core sections may be wound or active sections.

Many of the disadvantages inherent in the foregoing method of assembly are discussed in U.S. Pat. No. 3,417,465, the disclosure of which patent is herein incorporated by reference.

The method proposed by the aforesaid patent for dealing with certain of these disadvantages involves the formation of an elongate compound housing and the assembly therewith of a plurality of elongate compound cores, the opposite end portions of which are integral during this assembly operation but which are destined to become the coresections associated with opposed housing halves at a later stage in the manufacturing operation. This is accomplished by dividing each of the compound housingsand its assembled compound cores to yield the opposed halves of a magnetic head which are then joined together in a suitable manner to define a plurality of individual magnetic circuits as defined by the opposite end portions of the previously integral combination cores. One substantial advantage accruing from the method described in U.S. Pat. No. 3,417,465 is the fact that only half the number of cores and housings need be handled during the initial assembly stages and, even in the final assembly stages, only two housing sub-assemblies, which sub-assemblies include the previously assembled core sections, need be handled to produce a single magnetic head. This not only reduces manufacturing costs but makes possible the attainment of much closer manufacturing tolerances, since, among other reasons, both housing sections may be machined in a single pass.

SUMMARY OF THE INVENTION The instant invention constitutes an improvement over the method disclosed in U.S. Pat No. 3,417,465 primarily in that only two housing sub-assemblies are required to be worked or handled in the production of two complete magnetic heads as opposed to the required handling of two sub-assemblies in the production of a single magnetic head as described in the aforesaid patent.

Basically, nothing more is required than an end-for-end reversal of one of the elongate housing assemblies containing its previously assembled elongate compound cores relative to another like housing assembly whereupon the two housing assemblies are joined in faceto-face engagement to form an elongate composite head assembly which it is only necessary to divide intermediate the ends thereof to produce two complete magnetic heads. The end-for-end reversal of one of the sub-assemblies relative to the other before the same are joined insures that opposite end portions of the elongate cores will be appropriately positioned to define two magnetic circuit paths defined by each opposed pair of elongate cores. The division of the elongate composite head assembly at a position intermediate the core sections thus results in two magnetic heads each including a single magnetic circuit path defined by each opposed pair of the now divided core sections.

The end-for-end reversal technique is critical to the practice of the invention in the more usual case where the elongate combination core comprises both active and inactive sections. This for the reason that it is necessary that corresponding active and inactive sections be paired during the assembly of the elongate composite head assembly prior to its division.

The use of solid copper housing sections obviates the necessity for additional machining and/or assembly operations to provide intertrack shielding for reasons more fully enumerated in applicants copending application Ser. No. 142,673 filed May 12, 1971.

DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view illustrating the assembly of a plurality of compound cores with a pair of elongate housing members;

FIG. 2 is an exploded perspective illustrating the manner in which the elongate housing assemblies are joined to form an elongate composite head assembly; and

FIG. 3 is a schematic illustration of the separation of a composite head assembly to produce a pair of multiple track, single gap magnetic heads.

DESCRIPTION OF THE PREFERRED EMBODIMENT A pair of elongate, compound housing members 10, 12 may, if desired, be aligned generally after the manner shown in FIG. I for the machining of the nine core receiving recesses 14 and the horizontal alignment slot 16 in a single pass. A plurali ty of elongate, compound cores 18, including a previously wrapped active core portion 20 and a return core section 22 separated by a vertical alignment slot 24, are then assembled with each housing section and mutually aligned therein by the positionment of a vertical alignment pin, not shown, lying across the vertical alignment slot 26 formed in each housing member I0, 12 and engaging the vertical alignment slots 24 in the various compound cores 18.

In accordance with the particular compound core configuration illustrated herein; the active core section assumes the shape of a C core which has been previously wound with the transducing coil 28 in a conventional manner while the inactive core section is depicted as a simple 1" core. Each compound core 18 is positioned in its individual housing recess 14 as illustrated by the dashed assembly lines associated with housing 10 in FIG. 1. Following the assembly of all nine compound cores with their respective housing members, a vertical alignment pin, not shown, is used to align the cores as illustrated by the completed core assembly with housing 12 in FIG. 1. A plurality of male connectors are interconnected with transducer coils 28 and positioned in recesses 30 prior to the usual potting operation. The potting material and connector pins have been omitted from the drawing for clarity of illustration.

Thereafter the housing members are ground or lapped before being placed in face-to-face engagement in an end-forend reversed position as indicated by the arrow 32 in FIG. 1 following the positionment of a desired shim material, not shown, adjacent the pole tips 34 of each active core section 20 to define the necessary air gap between the pole tips and those ends of the associated I cores with which they will be related in the composite head assembly 36 indicated in FIG. 2. A horizontal alignment key 38, positioned as indicated in FIG. 2, insures that each compound core 18 in each housing member is precisely aligned with another compound core in the other housing section while the end-for-end reversal of the housing members insures that a magnetic circuit path, including an air gap, is defined by each C" core in one housing section in conjunction with an I core in the other housing section as will be apparent from an inspection of FIGS. 1 and 2. The housing members l0, 12 may be joined together in the composite head assembly in any conventional manner, such as by threaded fasteners (not shown), following which time the composite head assembly is divided, such as by parallel sawcuts 40 as indicated in FIG. 3, to produce two complete multiple track, single gap magnetic heads each of whose air gaps are adjacent the saw-cut portions.

We claim:

l. A method of manufacturing multiple track, single gap magnetic heads, comprising; providing a plurality of elongate, magnetic core members, each said member having first and second core portions spaced along the longitudinal axis thereof; providing a winding on each of said first portions, assembling a like number of similar members with each of two identical, elongate housings; joining the housing assemblies in face-to-face engagement with the first core portions of each housing assembly defining individual magnetic circuits, including transducing gaps, with the second core portions of the other housing assembly; and dividing the joined housing assemblies substantially perpendicular to the plane of their faceto-face engagement at a position intermediate the first and second portions of the core members to produce two single gap magnetic heads.

2. The method of claim 1 wherein said first core portions are wrapped with transducing coils to define active core sections and said second core sections comprise inactive return core sections.

3. The method of claim 1 wherein the step of joining the housing assemblies in face-to-face engagement includes an end-for-end reversal of the housing assemblies prior to the face-to-face joining thereof. 

1. A method of manufacturing multiple track, single gap magnetic heads, comprising; providing a plurality of elongate, magnetic core members, each said member having first and second core portions spaced along the longitudinal axis thereof; providing a winding on each of said first portions, assembling a like number of similar members with each of two identical, elongate housings; joining the housing assemblies in face-to-face engagement with the first core portions of each housing assembly defining individual magnetic circuits, including transducing gaps, with the second core portions of the other housing assembly; and dividing the joined housing assemblies substantially perpendicular to the plane of their face-to-face engagement at a position intermediate the first and second portions of the core members to produce two single gap magnetic heads.
 2. The method of claim 1 wherein said first core portions are wrapped with transducing coils to define active core sections and said second core sections comprise inactive return core sections.
 3. The method of claim 1 wherein the step of joining the housing assemblies in face-to-face engagement includes an end-for-end reversal of the housing assemblies prior to the face-to-face joining thereof. 